It is desirable to estimate the position (or “location”) of persons and things in a geographic area with a reasonable degree of accuracy. Accurate estimations of a position can be used to speed up emergency response times, track business assets, and link a consumer to a nearby business. Various techniques are used to estimate the position of an object, including trilateration, which is the process of using geometry to estimate a location of an object using distances traveled by different signals that are received at a location of the object, where the signals are transmitted from geographically-distributed transmitters.
In many urban terrestrial positioning systems, a line-of-sight (LOS) signal path from a transmitter to a receiver is blocked by buildings and the like, leaving only reflected paths over which signals travel from the transmitter to the receiver. This leads to less accurate estimates of a receiver's position, especially if the reflected path is a few hundred meters longer than the LOS path. To make matters worse, processing times must be kept to a minimum in order to determine a location of the receiver within strict time periods set by the government, commercial entities, or the demands of consumers. Accordingly, there is a need for improved position estimation techniques.